code: def diff(x: tf.Tensor, *, axis: int) -> tf.Tensor:
      s = [slice(None, None) for _ in x.shape]
      s[axis] = slice(None, -1)
      head = x.__getitem__(s)
      s[axis] = slice(1, None)
      tail = x.__getitem__(s)
      return tail - head
  
imports: from dataclasses import dataclass
  from typing import Any
  import numpy
  import pytest
  import tensorflow
  from check_shapes import ShapeChecker
  from gpflow.functions import Linear
  from gpflow.likelihoods import Beta, Gamma, Gaussian, ScalarLikelihood, StudentT
  from gpflow.utilities import to_default_float
label_desc: Use image node_id 1 for calling a global function with example usage: diff(x) and returns: unknown